Compressor cooling system

ABSTRACT

A compressor system that includes a compressor, a refrigeration system, a drive member and a cooling passage. The compressor is operable to produce a flow of compressed fluid. The refrigeration system includes an evaporator, and a flow of refrigerant passes through the evaporator and is operable to cool the flow of compressed fluid. The drive member is coupled to the compressor and is operable to drive the compressor. The cooling passage extends from a point downstream of the evaporator to a point upstream of the compressor. At least a portion of the cooling passage is in thermal exchange relationship with the drive member.

BACKGROUND

The present invention relates to a cooling system for use in a compressor system. More particularly, the present invention relates to a refrigeration system configured to cool components of a compressor system.

Compressor assemblies typically include a compressor that is driven by a drive member to create a flow of compressed fluid. The process of creating the flow of compressed fluid can produce a considerable amount of heat. Typically, the flow of compressed fluid exits the compressor at a high temperature. Therefore, the flow of compressed fluid is cooled before it is utilized. Furthermore, the heat generated by the compression process also raises the temperature of a fluid, such as oil, utilized by the compressor for lubricating, sealing and cooling. In addition, other components of the compressor system such as, the drive member, a variable frequency drive, and a control system can in some circumstances create undesirable amounts of heat that can damage these components or shorten their operating lives.

SUMMARY

In one embodiment, the invention provides a compressor system that includes a compressor that is operable to produce a flow of compressed fluid and a refrigeration system that includes an evaporator. The evaporator passes a flow of refrigerant therethrough and is operable to cool the flow of compressed fluid. The compressor system also includes a drive member that is coupled to the compressor and is operable to drive the compressor. A cooling passage extends from a point downstream of the evaporator to a point upstream of the compressor and at least a portion of the cooling passage is in thermal exchange relationship with the drive member.

In another embodiment the invention provides a method of operating a fluid compression system that includes coupling a compressor to a drive member and operating the drive member to produce a corresponding operation of the compressor to produce a flow of compressed fluid. The method also includes passing a flow of refrigerant through an evaporator to cool the flow of compressed fluid and passing the flow of refrigerant from the evaporator into a return line. A portion of the flow of refrigerant is diverted from the return line to the drive member to cool the drive member.

In yet another embodiment, the invention provides a fluid compression system that includes a plurality of compressors operable to provide a flow of compressed fluid and a plurality of drive members. Each drive member is associated with one of the compressors and is operable to drive the compressor. The system also includes a refrigeration system that includes a refrigeration compressor, operable to compress and discharge a flow of refrigerant. The flow of refrigerant is in thermal exchange relationship with the flow of compressed fluid such that the flow of refrigerant cools the flow of compressed fluid. A cooling passage is positioned to receive a portion of the flow of refrigerant. At least a portion of the cooling passage is positioned in thermal exchange relationship with one of the plurality of drive members to cool one of the plurality of drive members.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a compressor system embodying the present invention;

FIG. 2 is a schematic view of a portion of the compressor system of FIG. 1; and

FIG. 3 is a schematic view of another compressor system embodying the invention.

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,”

“supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a compressor system 10 that includes a compressor assembly 12 and a refrigeration system 14. The illustrated compressor assembly 12 includes a compressor 16, a drive member 18, a variable frequency drive (VFD) 20 and a control system 22.

The compressor 16 can be any suitable compressor design, such as a rotary screw compressor, a centrifugal compressor, or a reciprocating compressor. The illustrated compressor 16 includes a compressor outlet 24 and an after-cooler 26. The compressor outlet 24 is in fluid communication with the compressor 16 and the after-cooler 26. The compressor 16 also includes an oil cooler 28 and an oil passage 30. The oil passage 30 is in fluid communication with the compressor 16 and the oil cooler 28. While the illustrated compressor 16 includes the oil cooler 28 and the after-cooler 26, in other constructions the compressor 16 may omit one or both of the oil cooler 28 and the after-cooler 26.

Furthermore, while the illustrated compressor 16 is a single stage compressor, in other constructions, the compressor 16 can be a multi-stage compressor and can include an inter-cooler located between each stage. The inter-cooler is configured to cool the air or working fluid compressed by the compressor 16. In this arrangement, the output of the first compressor stage is directed to the inlet of the second compressor stage. This arrangement allows for a greater pressure increase, which may be necessary in some application.

Before proceeding, it should be noted that the term “passage” and “line” as used herein should be interpreted broadly. Specifically, the terms “passage” and “line” should be interpreted to include but not limited to, conduits, channels, tubes, pipes, valves, flanges, hoses, and the like. Thus, a “passage” or “line” is essentially any structural element that is able to direct fluid between first and second points.

Referring to FIG. 1, the drive member 18 is coupled to the compressor 16, and in one construction, includes a motor, such as a variable speed motor. In other constructions, the drive member 18 can include other suitable drive members, such as a turbine, an internal combustion engine, a diesel engine and the like.

The refrigeration system 14 includes a refrigerant compressor 32, a condenser 34, an expansion device 36, an evaporator 38 and a return line 40. As schematically illustrated in FIG. 1, the refrigerant compressor 32 is fluidly coupled to the condenser 34. The condenser 34 is fluidly coupled to the expansion device 36 and the expansion device 36 is fluidly coupled to the evaporator 38. The evaporator 38 is in thermal exchange relationship with the compressor outlet 24 downstream of the after-cooler 26 to cool the air or working fluid compressed by the compressor 16. The evaporator 38 includes an evaporator outlet 42 that is fluidly coupled to the return line 40. The return line 40 fluidly couples the evaporator outlet 42 to the refrigerant compressor 32 to return refrigerant to the refrigerant compressor 32 and complete the cycle. While the illustrated refrigeration system 18 includes a single refrigerant compressor 32, condenser 34, expansion device 36, evaporator 38, and return line 40, in other constructions, the refrigeration system 18 can include multiple refrigerant compressors 32, condensers 34, expansion devices 36, evaporators 38, and return lines 40, as may be desired. In addition, as one of ordinary skill in the art will realize, refrigeration systems may include other components not illustrated in FIG. 1. These additional components include tanks, valves, sensors, separators, and the like. As such, the refrigeration system should not be limited to the components illustrated in FIG. 1.

As illustrated in FIG. 1, the refrigeration system 14 defines a portion of an air dryer system 44. The air dryer system 44 includes the refrigerant compressor 32, the condenser 34, the expansion device 36 and the evaporator 38. It should be understood that in other constructions, the air dryer system may not include the refrigeration system 14 and may include another suitable air dryer design, such as a desiccant type air dryer. In such a construction, the refrigeration system 14 would be a separate system, independent of the air dryer 44. In yet another construction, the air dryer system 44 can employ a refrigeration system separate and distinct from the refrigeration system 14.

With continued reference to FIG. 1, a cooling passage 46 is in fluid communication with the return line 40 to draw a portion of the refrigerant from the refrigeration system 14 after the refrigerant has passed through the evaporator 38. It should be understood that the cooling passage 46 can connect to the return line 40 at any point between the evaporator 38 and the refrigerant compressor 32. In other constructions, the cooling passage 46 connects directly to the evaporator 38 or to another point within the refrigeration system 14. In preferred constructions, the cooling passage 46 may include a pipe, a tube, or other conduit.

The cooling passage 46 may include a plurality of portions 48 that are in thermal exchange relationship with one or more of the after-cooler 26, the oil cooler 28, the drive member 18, the VFD 20, the control system 22, or other components within the compressor system (e.g., gearbox). Each of the plurality of portions 48 includes a flow path that directs a portion of refrigerant to a component to be cooled. In preferred arrangements, each of the plurality of portions 48 includes a heat exchanger that allows the flow of refrigerant to cool the component to be cooled with greater efficiency.

As schematically illustrated in FIG. 2, in one construction, one of the plurality of cooling passage portions 48 includes a heat exchanger 50 configured to allow the flow of refrigerant to cool the drive member 18. In such a construction, a fan 51 is driven by the drive member 18 or a separate fan drive member, to move air across the heat exchanger 50. The air that passes across the heat exchanger 50 is cooled and then passes across the drive member 18 to cool the drive member 18. In one construction the separate fan drive member can be an electric motor, and in such a construction, the motor can be selectively turned off and on to control the amount of air that moves across the heat exchanger 50 and the drive member 18. A temperature switch, or other suitable device, can be used to start and stop the fan drive member when the drive member 18 has reached predetermined temperatures. For example, the temperature switch can be configured to turn on the fan drive member when the temperature of the drive member 18 exceeds a predetermined temperature, and the temperature switch can be configured to turn off the fan drive member when the temperature of the drive member 18 falls below a predetermined temperature.

The heat exchanger 50 and the fan 51 illustrate just one possible arrangement of a thermal exchange relationship between one of the cooling passage portions 48 and the drive member 18. It should be understood that any suitable thermal exchange relationship between the plurality of cooling passage portions 48 and the after-cooler 26, the oil cooler 28, the drive member 18, the VFD 20, or the control system 22 can be utilized.

A valve, or other suitable control device, can be disposed in the cooling passage 46 or in the return line 40 to provide selective fluid communication between the evaporator outlet 42 and the cooling passage 46. In other constructions, a valve may be disposed in any one of, or each of the plurality of cooling passage portions 48 to provide selective fluid communication between the evaporator outlet 42 and the cooling passage portion 48.

FIG. 3 illustrates an alternative construction in which a compressor system 10′ includes a plurality of compressor assemblies 12′ and a refrigeration system 14′. Although three compressor assemblies 12′ are illustrated, it should be understood two compressor assemblies or four or more compressor assemblies can be utilized as desired.

As schematically illustrated in FIG. 3, each of the compressor assemblies 12′ includes a compressor 16′. The compressors 16′ can be any suitable compressor design, such as rotary screw compressors, centrifugal compressors, reciprocating compressors, or any combination thereof. The illustrated compressors 16′ each include a compressor outlet 24′ that is fluidly coupled to an outlet header 54. In other constructions, the compressor outlets 24′ may not be fluidly coupled to the common outlet header 54, and the outlets 24′ can remain independent to their respective compressor 16′.

A drive member 18′, an after-cooler 26′, an oil cooler 28′, a VFD 20′ and a control system 22′ may be associated with each one of, or all of the plurality of compressors 16′. In another construction, each of the compressor assemblies 12′ may omit one or more of the after-cooler 26′, the oil cooler 28′, the VFD 20′ and/or the control system 22′. In these constructions one control system, a single oil cooler, or a single after-cooler may function to control the entire compressor system 10′, cool all of the system oil, or cool all of the compressed air (or other fluid) discharged by the compressors 16′.

It should be understood that the remainder of the compressor system 10′ illustrated in FIG. 3, including the refrigeration system 14′, is substantially the same as the compressor system 10′ illustrated in FIG. 1. Therefore, similar items have been given similar reference numbers.

The operation of the compressor systems 10, 10′ of FIGS. 1 and 3 are similar in many ways. Therefore, only the operation of the compressor system 10 of FIG. 1 will be discussed in detail. In operation, the drive member 18 drives the compressor 16 to produce a flow of compressed fluid, typically air. The flow of compressed fluid exits the compressor 16 and passes to the compressor outlet 24.

The compressor outlet 24 directs the flow of compressed fluid to the after-cooler 26 that is configured to cool the flow of compressed fluid. The flow of compressed fluid exits the after-cooler 26 and flows to the evaporator 38 that defines a portion of the air dryer system 44. The evaporator 38 is configured to further cool the flow of compressed fluid to allow the air dryer 44 to reduce the amount of moisture contained within the flow of compressed fluid. The flow of compressed fluid exits the evaporator 38 and flows through the remainder of the air dryer 44 before being passed to equipment that utilizes the flow of compressed fluid.

The VFD 20 operates to vary the rotational speed (i.e. revolutions per minute) of the associated drive member 18 in response to one or more control signals. Changing the rotational speed of the drive member 18 results in a corresponding change in the rotational speed of the compressor 16. By varying the rotational speed of the compressor 16, the volume of compressed fluid discharged by the compressor 16 can be varied.

The control system 22 controls the operation of the compressor assembly 12. For example, the control system 22 may control the loading and unloading of the compressor 16 or may cycle the compressor 16 on and off. The control system 22 may also monitor various operating parameters of the compressor assembly 12, such as an outlet fluid pressure, an oil temperature, an outlet fluid temperature, etc. In addition, the control system 22 controls the VFD 20 to control the rotational speed of the compressor 16 and the volume of compressed fluid discharged by the compressor 16.

A flow of oil is utilized by the compressor 16 to lubricate and cool components of the compressor 16, such as screw rotors and bearings. During operation of the compressor 16, the temperature of the flow of oil can increase and it may be desirable to cool the flow of oil. In one construction, the flow of oil exits the compressor 16 through the oil passage 30 and is passed to the oil cooler 28. The oil cooler 28 cools the flow of oil and then the oil passage 30 directs the flow of oil back to the compressor 16 to be re-used to cool and lubricate the compressor components.

The refrigeration system 14 is operable to produce a cool flow of refrigerant. The flow of refrigerant may include any suitable refrigerant, such as argon or FREON. The refrigeration compressor 32 is configured to create a compressed flow of refrigerant that exits the refrigeration compressor 32 and passes to the condenser 34. The condenser 34 removes heat from the flow of refrigerant, thereby at least partially condensing the flow of refrigerant. Next, the flow of refrigerant enters the expansion device 36 where it is expanded, thereby causing a reduction in the pressure and temperature of the flow. The expanded flow of refrigerant exits the expansion device 36 and passes to the evaporator 38 where the flow of refrigerant is in thermal exchange relationship with the flow of compressed fluid, such that the flow of refrigerant cools the flow of compressed fluid.

The flow of refrigerant exits the evaporator 38 through the evaporator outlet 42 and flows to the return line 40. A portion of the flow of refrigerant may be diverted from the return line 40 to the cooling passage 46. In the cooling passage 46, the portion of the flow of refrigerant can be further diverted into portions that are passed to the plurality of cooling passage portions 48. One of the plurality of cooling passage portions 48 may be in thermal exchange relationship with the drive member 18 and the flow of refrigerant within the cooling passage portion 48 is operable to cool the drive member 18. Another one of the cooling passage portions 48 may be in thermal exchange relationship with the after-cooler 26, such that the flow of refrigerant is operable with the after-cooler 26 to cool the flow of the compressed fluid. Yet another cooling passage portion 48 may be in thermal exchange relationship with the oil-cooler 28, such that the flow of refrigerant is operable with the oil-cooler 28 to cool the flow of oil. The cooling passage portions 48 may also be in thermal exchange relationship with the VFD 20 and the control system 22, such that the flows of refrigerant within the cooling passage portions 48 are operable to cool the VFD 20 and the control system 22. In other constructions, one of the cooling passage portions 48 can be in thermal exchange relationship with the inter-cooler or inter-coolers that are configured to cool the flow of compressed fluid between each stage of compression.

It should be understood that although the illustrated compressor assembly 12 includes the after-cooler 26, the oil-cooler 28, the drive member 18, the VFD 20 and the control system 22 all in thermal exchange relationship with portions 48 of the cooling passage 46, it is not necessary for all of these components to be in thermal exchange relationship with the cooling passage 46. For example, in one construction the oil-cooler 28 can be air cooled and therefore, the oil cooler 28 may not be in thermal exchange relationship with the cooling passage 46. In yet another construction, the after-cooler 26, the oil-cooler 28, the VFD 20 and the control system 22 are all air cooled and only the drive member 18 is in thermal exchange relationship with the cooling passage 46. Thus, as one of ordinary skill will realize, any one or combination of the components can be cooled using the refrigeration system 14 described herein.

After the portions of the flow of refrigerant complete the thermal exchange relationship with the after-cooler 26, the oil cooler 28, the drive member 18, the VFD 20 and/or the control system 22, the portions of the flow of refrigerant are passed into the return line 40. The return line 40 collects the portions of the flow of refrigerant, along with the portion of the flow of the refrigerant that was not passed through the cooling passage 46, and returns the flow of refrigerant back to the refrigerant compressor 32. The flow of refrigerant returned to the refrigerant compressor 32 repeats the refrigeration process described above to create the cool flow of refrigerant.

Thus, the invention provides, among other things, a compressor system 10 that includes a compressor 16, a drive member 18 and a refrigeration system 14. The refrigeration system 14 may operate as part of an air dryer 44 to dry the compressed fluid exiting the compressor 16 and is also operable to cool other components such as the drive member 18, a variable frequency drive 20, a control system 22, an after-cooler 26, and/or an oil cooler 28. 

1. A compressor system comprising: a compressor operable to produce a flow of compressed fluid; a refrigeration system including an evaporator, the evaporator passing a flow of refrigerant therethrough and operable to cool the flow of compressed fluid; a drive member coupled to the compressor and operable to drive the compressor; and a cooling passage extending from a point downstream of the evaporator to a point upstream of the compressor, at least a portion of the cooling passing in thermal exchange relationship with the drive member.
 2. The compressor system of claim 1, wherein the drive member includes a motor.
 3. The compressor system of claim 2, wherein the drive member includes a variable frequency drive, and wherein at least a portion of the flow of refrigerant within the cooling passage is operable to cool at least one of the motor and the variable frequency drive.
 4. The compressor system of claim 1, wherein the compressor includes an oil cooler, and wherein at least a portion of the flow of refrigerant within the cooling passage passes through the oil cooler to cool a flow of oil.
 5. The compressor system of claim 1, wherein the compressor includes a control system, and wherein at least a portion of the flow of refrigerant within the cooling passage is operable to cool the control system.
 6. The compressor system of claim 1, further comprising a heat exchanger positioned within the cooling passage, at least a portion of the flow of refrigerant within the cooling passage passing through the heat exchanger to cool the drive member.
 7. A method of operating a fluid compression system, the method comprising: coupling a compressor to a drive member; operating the drive member to produce a corresponding operation of the compressor to produce a flow of compressed fluid; passing a flow of refrigerant through an evaporator to cool the flow of compressed fluid; passing the flow of refrigerant from the evaporator to a return line; diverting a portion of the flow of refrigerant from the return line to the drive member to cool the drive member.
 8. The method of claim 7, wherein the drive member includes a motor.
 9. The method of claim 7, further comprising directing a portion of the refrigerant from the return line to an oil cooler to cool a flow of oil.
 10. The method of claim 7, further comprising directing a portion of the refrigerant from the return line to a variable frequency drive to cool the variable frequency drive.
 11. The method of claim 7, further comprising directing a portion of the refrigerant from the return line to a control system to cool the control system.
 12. The method of claim 7, further comprising directing a portion of the compressed fluid from the compressor through the refrigeration system to cool the flow of compressed fluid.
 13. A fluid compression system comprising: a plurality of compressors operable to provide a flow of compressed fluid; a plurality of drive members, each drive member associated with one of the compressors to drive the compressor; a refrigeration system including a refrigerant compressor operable to compress and discharge a flow of refrigerant, the flow of refrigerant in thermal exchange relationship with the flow of compressed fluid such that the flow of refrigerant cools the flow of compressed fluid; and a cooling passage positioned to receive a portion of the flow of refrigerant, at least a portion of the cooling passage positioned in thermal exchange relationship with at least one of the plurality of drive members to cool the at least one of the plurality of drive members.
 14. The fluid compression system of claim 13, wherein at least one of the plurality of drive members includes a motor.
 15. The fluid compression system of claim 14, wherein at least one of the plurality of drive members includes a variable frequency drive.
 16. The fluid compression system of claim 13, further comprising a control system operable to control the plurality of compressors and in thermal exchange relationship with at least a portion of the cooling passage to cool the control system.
 17. The fluid compression system of claim 13, wherein at least one of the plurality of compressors includes an oil cooler in thermal exchange relationship with at least a portion of the cooling passage to cool a flow of oil.
 18. The fluid compression system of claim 13, further comprising a heat exchanger positioned within the cooling passage to cool at least one of the drive members.
 19. The fluid compression system of claim 13, wherein the refrigeration system includes an evaporator having an outlet.
 20. The fluid compression system of claim 19, further comprising a return passage extending from the outlet to the refrigerant compressor, the cooling passage connected to the return passage to receive the portion of the flow of refrigerant. 